What the Fancy Machines Can — And Can't — Do

Dr. Scott Haig is an Assistant Clinical Professor of Orthopedic Surgery at Columbia University College of Physicians and Surgeons. He has a private practice in the New York City area.

An MRI scanner is an amazing thing; it can detect some tumors that are only the size of a grain of rice. Here's roughly how it works: You hold really still for half an hour or so in a big machine made of a magnet and some computers. The magnet itself is big, heavy and expensive  not to mention so strong that it could pull on a paper clip with nearly 100 pounds of force. You're blasted with strong radio waves. The protons in your body absorb some radio waves, then they let some back out  like a crystal wine glass ringing after a great soprano sings at it. The machine "listens" to the radio waves that come back out with a bunch of little antennas and then, by comparing the output of the antennas and doing a few hundred million simple calculations, it determines, roughly, how much water and fat was around the protons in a single tiny spot. The relative amount of water and fat at that spot in you determines how light or dark a little spot on the picture will be. Do this for a few hundred thousand spots and, voila, a detailed (though still far from perfect) picture of one slice of one part of your body.

Dr. Scott Haig is an Assistant Clinical Professor of Orthopedic Surgery at Columbia University College of Physicians and Surgeons. He has a private practice in the New York City area

As awesome as it is, an MRI is only one of the diagnostic tests at a physician's disposal. A PET scan, for instance, is even more complicated, measuring how much energy is being used by your cells in order to give an energy-use mapping of a slice of your body. It is better at showing some tumors than any other imaging method. We have tri-spiral CT scanners, radionucleide bone scanners, EKG-gated CT angiographic scanners. We can test the electrical activity of brain, muscle and nerve. We can test your blood in two thousand different ways. We can test the gases going in and out of your lungs.

We have so many tests I can't write them all down. They are all expensive. They are all designed to detect pathology  in other words, something wrong. And unfortunately, at one point or another in every person's life, none of them can really help cure us. All they can do then is give what ails us a name, tell us that someone has seen this before, and remind us not to expect too much.

Dr.Don DiPietro had pathology. He was slurring his speech, stumbling as he walked, so much so that people thought he was drunk. Don was one of the best cardiologists at our hospital, a heart specialist who was also a "real doctor," and he diagnosed and treated everything he could. An Ivy-league graduate with a fascination for the Sopranos world, he had his eccentricities. But Don was a pillar of our medical community, smart, hard-working and always attuned to the subtleties.

Don's patients were as loyal as they come. People outside the world of medical specialists don't appreciate how certain internists have certain kinds of patients. It's amazingly consistent  rather like pet owners resembling their pets. Nervous, frightened internists have nervous, frightened patients. Puffed-up, formal ones have puffed-up, self-important patients. Nice guys have friendly, reasonable patients. Don had great patients. When we discussed them he knew every little fact about them.

But now Don himself was the patient under discussion. When we had a moment alone in the doctor’s lounge, I asked him "what's going on?" We talked about tests. It had to be his brain. His wise head therefore ordered itself shot through with x-rays, ultrasonic waves, magnet fields of strength found only around spinning stars, radio waves, injections of iodine, gadolinium, positron-emitting glucose. Many other brains were wracked for the sake of his; neurologists, neuroradiologists, infectious disease specialists. Tens of thousands of dollars of tests. No diagnosis.

Finally, Don himself remembered that he used to play with the mercury from his office blood-pressure machine—with his bare hands  back before we knew much about the toxicity of mercury. There was a big "aha" from the neurologists. It was a subtle, localized brain disease related to mercury poisoning. It was a diagnostic victory, won largely by a sick brain, Don’s brain, trying to cure itself.

They called it a supra-nuclear palsy, and it was rare. Now, I thought, they could get down to fixing it, curing the sickness, making him better. I talked to Don. Got a diagnosis  great. But I saw that Don knew something dark about disease, this neurologic disease in particular. Keeping that dark thing as far in the back of his mind as he could, he looked it up: in the most recent textbooks, in the best journals, then in the not-so-hot journals. Through page on page, volume after volume, he grappled with the dark thing but couldn't get away. Not a ray of light. "Supra-nuclear palsy is relentlessly progressive, untreatable." Poor Don. He knew it would kill him  and it did.

The dark thing about medicine is that one thing or another gets every last one of us. We chalk up some great games but we never win in the finals. The big machines and fancy tests so often do only what they did for Don.

The flip side of this sad thought is one of our happiest, however. It's the reason why older doctors (when they're not thinking about HMO's) are generally a stable and contented bunch. Most of the time, most of our bodies work pretty well. Without a superconducting, supercooled magnet, without medical education, without any thought on our part, we battle and defeat disease and injury every second. Do you know how many things out there can kill you? Yet here you are reading. Something very, very powerful must be keeping you here. The machines we have to analyze the body are complex. But not nearly as complex, or as wondrously made and maintained, as the human body itself.